Method of making polygonal tubes



No. 6l5,7 0 l. Patented Dec. l3, I898.

C. P. HIGGINS.

METHOD OF MAKING PULYGONAL TUBES.

(Application filed Mar. 13, 1897.)

(No Model.)

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NITED STATES PATENT FFICE.,

CAMPBELL P. HIGGINS, OF ROSELLE, NEXV JERSEY.

METHOD OF MAKING POLYGONAL TUBES.

SPECIFICATION forming part of Letters Patent No. 615,701, dated December 13, 1898.

Application filecl March 18, 1897. $erial1lo. 627,397. (No model.)

To all whom it may concern:

Be it known that I, CAMPBELL P. HIGGINS,

a citizen of the United States, residing at B0- selle, in the county of Union and State of New Jersey, have invented a new and useful Improvement in Methods of Making Polygonal Tubes, of which the following, taken in connection with the accompanying drawings, is a specification;

This invent-ion is intended for special use' viz., in the manufacture of headers for sectional steam-generators. It is obvious, however, that it may be utilized for many other purposes.

The invention consists in bending a plate of metal into a trapezium shape in cross-section so as to lap at' one angle or corner, this angle formed at the lap being more acute than at the opposite corner of the tube, as shown in the perspective view, Figure 1, and

end views, Figs. 2 and 3, of the drawings. This may be accomplished in various well-known ways with clamp-bending or mandrel and die machines. The tube or box thus formed presents but one longitudinal seam at one angle or corner. This angle or corner is then heated to a welding-point either in a furnace, as shown in Fig. 2, or in any other convenient device, and then subjected to the action'of a rapidly-acting trip-hammer, (represented in Fig. 3,) which compresses the tube into its perfect rectangular shape and causes an increased compression at the lapped corner to form the weld; The tube when completed is shown in its perfect rectangular shape in the perspective view, Fig. 4.

The faces of the anvil and hammer are made, preferably, of sufficient width to substantially encompass the tube. These faces are rectangular and correspond to the finished shape of the tube in cross-section. The first contact of the hammer with the tube is at the extreme point or apex of the lapped corner, due to the trapezium shape of the latter.

The advantages attending the use of this invention are principally in the welding operation, the trapezium form of the box and rectangular shape of the face of the hammer acting to effectively close the lap and form a perfect weld. The hammer is preferably made to operate by a succession of short rapid blows as the tube is passed to and from beneath it.

No mandrel is used or required. The form of the anvil and hammer and the corresponding position of the tube will sustain all the force that is essential to a perfect welding operation.

What I claim, and desire to secure by Letters Patent, is-

The method described of making polygonal tubes, consisting in first bending a plate to a trapezium shape in cross-section and to lap at one corner; second, subjecting said corner directly to heat, and third compressing the lapped corner to Weld the same and shape the tube to a rectangular cross-section.

CAMPBELL P. rneems.

Witnesses:

O. W. FORBES, E. L. Tonn. 

